The BIOS (basic input/output system) is built-in software that determines what a computer can do without accessing programs from a disk. On PCs, the BIOS contains all the code required to control the keyboard, display screen, disk drives, serial communications, and a number of other functions. The BIOS is typically placed on a writeable chip that comes on the motherboard. This ensures that the BIOS will always be available and will not be damaged by disk failures. The BIOS also contains a boot program that provides the initial instructions to the computer processor at startup. These initial instructions contained in the boot program allow the computer to boot itself.
FIG. 1 illustrates the boot path 100 of a typical computer according to the prior art. The boot path includes a central processing unit (CPU) 105, a chipset 110, and a BIOS EPROM (erasable programmable read-only memory) 125. When a computer is first powered on, an initial set of instructions must be executed to allow the computer to boot itself. The CPU 105 is set to execute instructions that are located at the top of the computers memory located within the chipset 110. At power-up, there are typically no instructions present at these locations. Thus, the computer cycles forward to the BIOS EPROM 125. The BIOS EPROM 125 contains an initial set of boot instructions which are transferred to the chipset 110. The CPU 105 then reads the boot instructions from the chipset 110 and executed the instructions to boot the computer.
If the BIOS EPROM 125 is corrupted or missing, the initial set of boot instructions cannot be executed by the CPU 105. Thus, the CPU 105 is unable to boot the computer. In this circumstance, some computers allow the system to boot from the peripheral component interconnect (PCI) adapter. To accomplish this, hardware having a PCI interface is connected to the PCI bus. Because connections to the PCI bus are located on the computers motherboard, this procedure requires opening the housing of the computer.
If the BIOS does not exist or has been corrupted, existing systems allow the processor to boot from a peripheral component interconnect (PCI) adapter. This requires a user to open the housing of the computer to access the PCI adapter. It is typically undesirable to have a user open the housing of a computer. Even with trained service personnel, it would be more convenient to boot the computer without accessing the PCI adapter. This is especially true with systems having cases that are sealed or difficult to open, such as notebook computers.